Hello,
I did a quick search but didn't find appropriate results.
I just updated my Kobo Glo firmware to 2.3.1 from 2.1.5 - which was installed when I bought the device.
I try to convert everything to epub, but with some pdf files it's just not possible or at least too complicated for me to get a decent epub rendering (when they are image-heavy, when they have footnotes, etc.).
With 2.1.5, I used to read most of my pdf files in landscape mode. It was far from perfect but it usually did the job. I used to read while being zoomed in just enough to have no text trespassing the lateral borders of the screen, then I scrolled down to the end of the page, and then scrolled back to the top just before turning the page by scrolling to the far right and tapping the black area on the right.
Now with the 2.3.1 firmware, it's a no-go. Some of my pdfs are perfectly readable with no zoom at all in portrait mode, but when I have to use landscape mode (when there is too much text on each line or margins that are too big for the text to be big enough to be readable with zoom off or even with zoom on in portrait mode), it's not even barely usable.
With many pdfs in landscape mode, when zoomed in, the upper part of the screen is simply missing. The first line or the first two lines of text are simply not displayed, no matter how hard I try to scroll up. These lines show again when I switch back to portrait mode, but then again it's generally too small to be readable.
So basically I'm stuck with many unreadable pdfs (for instance, most of my public-domain philosophy books, which make heavy use of footnotes and cannot be easily converted or cropped).
Did anyone notice this issue and find a solution ?
Thanks in advance,

PS. If I can't solve this issue, I'm considering switching back to 2.1.5. Can this be easily done, given that I don't really care loosing my stats or even shelves and use that I use calibre to handle my library ?

As davidfor says I went through too many steps but you can get the idea of how to do it. I love 2.1.5 compared to 2.3.[0?] although I found that PDF's worked ok for me. Still, I am reading a pdf at the moment on 2.1.5 and it is really fine -- everything is clear and easy to navigate.

You mention scrolling back to the top before changing the page -- I haven't found this to be necessary. At the bottom of the page just drag to the left. Let the screen redraw and touch the black bar. Then, in 2.1.5 after the first touch you are back at the top of the next page even though it shows the bottom of the page before the first touch.

Really, the Touch at least is fine with pdf's -- I don't know what people here are complaining about.

Pages under 2.3.2 are displayed left/top aligned (not centered as in 2.1.5) and in zoom mode everything on the right side is covered with the black bar preventing reading (the uncomplete) remaining of the page.
Also as indication that something must be wrong the zoom frame is not showing the the correct position.

tombo : Yes I noticed that too on some pdfs. Also sometimes for no reason that black bar is simply missing until I reload the file. Pdf behavior has become totally inconsistent, in addition to being buggy. And indeed they can't keep claiming pdf ain't their priority while in the same time pusing pdf papers on their device. I reported the first bug yesterday on their live chat, but I won't hold my breath.

voidoid : Indeed I got the idea of how to get back to 2.1.5 by reading your post. Thank you for this. I simply did a factory reset, then powered up the Kobo app to activate the device, then I deleted the 3 update files and replaced them by the 2.1.5 files just before disconnecting and here we go, I'm back to 2.1.5 and mostly happy with it.

Glad I found help on this forum and happy to join this helpful community,
Cheers,

I am having the exact same issue and instead of going through the trouble of factory resetting my blasted device I would just prefer if Kobo fixed the issue. I use my eReader primarily for .pdfs (academic papers) and this latest update has rendered the device entirely unusable for me (with term starting on Monday). I wish I could recommend my Kobo to others but issues like this FORCE me to tell others to look elsewhere! I am posting here in the vain hope that someone with influence will listen and fix a basic feature so I can at least use my device instead of glare at it!

I have the exact same issue. I noticed that there were some interface changes in the latest firmware, which may be related to this problem.

Another change I have noticed from earlier firmwares is that when turning the page, the position of the pdf doesn't change. So if I have scrolled all the way to the bottom right of the page to turn the page, the next page is loaded pre-scrolled to the bottom right. In previous firmwares (~1.9.17ish) it would snap to the top left. Inevitably it would still be necessary to drag the page to remove the top and left margins, but this was less hassle than having to drag the page to the top each time.

I also have the same problem! My device is rather old. I did a factory reset and the version I have is 1.9.4. I am amazed by how fast it is in comparison to the last several updated firmwares. the only problem is that it does not contain the dictionary software (they have added the dictionary from 1.9.6 on).